For convenience, this invention will be described in the context of an angioplasty procedure as a prime example of the use of guidewires.
The guidewire is relied upon for the proper placement of an angioplasty catheter at the region of a stenosis. With its slightly bent distal tip, the guidewire can be steered into the appropriate arterial branches by manual rotation of the guidewire at its proximal end while the guidewire is advanced.
Manipulation of the guidewire in this manner requires a device known as a "gripping device," "steering device" or "torque device" since the wire itself is of a very small diameter. The torque device, which is secured to the distal end of the guidewire, is large enough to be comfortably and securely gripped by the user's hand. The device, which is generally cylindrical in shape and has a knurled outer surface for easy handling, grips the guidewire in a manner which is secure and yet readily releasable so that the device can be slid back along the guidewire to permit further advancement of the guidewire.
Currently used torque devices require two hands for both tightening and releasing, one hand to grip the body of the device and the other to tighten or loosen the gripping mechanism inside the device. Since one hand is generally used to hold the catheter, the user who is advancing the guidewire through the vasculature must release his hold on the catheter each time the torque device is to be repositioned on the guidewire. Since the the device is typically repositioning on the guidewire for every advancement of 2-3 centimeters of the length of the guidewire, these devices can detract from the efficiency of a procedure where economy of time is critical to the survival of the patient. Devices which can be operated with one hand are known in the literature, but these are structurally inferior since they lack the ability to strongly grip the guidewire.